---
id: CVE-2021-45756
title: >-
  Asus RT-AC68U <3.0.0.4.385.20633 and RT-AC5300 <3.0.0.4.384.82072 are affected
  by a buffer overflow in blocking_request.cgi.
summary: >-
  Asus RT-AC68U <3.0.0.4.385.20633 and RT-AC5300 <3.0.0.4.384.82072 are affected
  by a buffer overflow in blocking_request.cgi.
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-120
vendor: asus
product: rt-ac68u_firmware
affected:
  - rt-ac68u_firmware < 3.0.0.4.385.20633
  - rt-ac5300_firmware < 3.0.0.4.384.82072
patched:
  - rt-ac68u_firmware 3.0.0.4.385.20633
  - rt-ac5300_firmware 3.0.0.4.384.82072
published: '2022-03-23'
updated: '2026-07-05'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-45756'
references:
  - url: 'https://github.com/IBUILI/Asus'
    label: cve@mitre.org
  - url: 'http://asus.com'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'http://rt-ac68u.com'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://github.com/IBUILI/Asus'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
epss: 0.01243
epssPercentile: 0.67912
ingestedAt: '2026-07-06T02:09:23.440Z'
---

## Overview

Asus RT-AC68U <3.0.0.4.385.20633 and RT-AC5300 <3.0.0.4.384.82072 are affected by a buffer overflow in blocking_request.cgi.

## Affected

- `rt-ac68u_firmware < 3.0.0.4.385.20633`
- `rt-ac5300_firmware < 3.0.0.4.384.82072`

## Remediation

Upgrade past the affected range:

- `rt-ac68u_firmware 3.0.0.4.385.20633`
- `rt-ac5300_firmware 3.0.0.4.384.82072`